This invention relates generally to a machine for applying a finish to the exterior surfaces of containers, such as cylindrical cans and, in particular, is directed to a portion of such machine for applying a finish to the bottom rim of a cylindrical can.
In general, a variety of machines for applying decorative finishes to containers such as cans and the like are known and comprise an infeed or conveyor assembly that transports the cans to a positioning unit that receives the cans and moves them into position for transfer to corresponding mandrels located on an axially adjacent rotatable mandrel wheel. After the cans are received on the corresponding mandrels, the mandrels are rotated into position for the printing operation, where a printing blanket is brought into contact with each of the containers, to place a decoration on the outer cylindrical surface thereof. Thereafter, the mandrels bearing the containers are moved to another location where a coat of varnish is applied to the decorated outer surface of each can to finish the decoration thereon. With conventional high speed continuously operating machines, the varnish is cured in an oven, while with slower intermittently operated machines, the varnish is cured by ultraviolet light at a subsequent station or by an oven.
Varnish is also desirably applied to coat the bottom rim of each can in order to protect the bottom rim from aluminum oxide deposited thereon during subsequent travel through the system. In the instance of continuously operating machines, the cans are removed from the aforementioned printing and varnishing stations by a pin chain and may be inclined thereon at an angle of approximately 10 degrees with respect to the mandrel assemblies. Varnish is applied to the bottom rim with a flat roller, and thereafter, the container with the varnished bottom rim and varnished cylindrical surface is transported to an oven where the varnish is cured.
With conventional intermittently operating machines which coat the bottom rims of the cans, the varnish on the bottom rim is applied and dried in the same manner as the aforementioned continuously operating machines.
It is to appreciated that the oven in the continuously operating machines is necessary to cure the varnish on the cylindrical surfaces which is not dried or cured when exiting on the pin chain. By contrast, intermittently operating machines which utilize ultraviolet light to dry the varnish on the cylindrical surfaces before the cans leave on the pin chain do not require an oven. The application of varnish to the bottom rims of the cans while on the pin chain in such an intermittently operating machine would therefore require the addition of an oven to cure or dry such varnish, which oven is otherwise not required.